Information recording medium, and method of manufacturing information recording medium

ABSTRACT

An information recording medium ( 100 ) is an optical recording medium in which a groove is made along a recording track and record or reproduction is carried out by irradiating laser light to it and a push-pull signal, which is smaller than a prescribed value, is obtained from a part of a region ( 101   a ) of the groove.

TECHNICAL FIELD

The present invention relates to an information recording medium such asa DVD and a BD (Blu-ray Disc), and a method of manufacturing theinformation recording medium.

BACKGROUND ART

A patent document 1 or the like discloses a distribution system; inwhich recording-type information recording media such as DVD-R/RWs aresold with encryption information pre-recorded; and in which encryptedDVD video contents (hereinafter referred to as “encrypted contents” asoccasion demands) are distributed through a network. In the distributionsystem, the encryption information applied to conventional read-onlytype media such as DVD-ROMs is pre-recorded before sale in a controlarea, such as a control data zone, on information recording media havingthe same physical structure as that of the conventional recording-typeinformation recording media such as DVD-R/RWs.

Moreover, the conventional recording-type information recording media(recording-type media) are designed as follows; namely, in therecording-type information recording media, firstly, contents such asmovie contents that allow arbitrary copy, which does not requirecopyright protection, i.e. copy-free contents, can be recorded on thebasis of a DVD-Video format, and then, a finalize process can beperformed. In addition, in the finalized recording-type informationrecording media, the reproduction can be performed while maintainingreproduction compatibility by conventional players (general informationrecording/reproducing apparatuses) such as DVD players.

On the one hand, in the DVD-Video format, copyright protection isrealized by an encryption system such as CSS (Content Scramble System).Specifically, if contents whose copyright is protected by the CSS arerecorded on the recording-type information recording media, areproduction restriction system for the copyright protection of theplayers does not allow the contents to be reproduced from therecording-type information recording media, and it uniformly forbids thereproduction of the contents. This is because, in general, theconventional players recognize that the contents whose copyright isprotected by the CSS are pre-recorded only on the read-only informationrecording media such as a DVD-ROM. Thus, the conventional players judgethat illegal content copy is performed if the contents whose copyrightis protected by the CSS are recorded on the recording-type informationrecording media. The reproduction restriction system does not allow thereproduction of the contents, and it uniformly forbids the reproductionof the contents. Incidentally, some players judge whether or not to bethe recording-type information recording media, (i) on the basis ofwhether or not a signal from wobble unique to the recording-typeinformation recording media (hereinafter referred to as a “wobblesignal” as occasion demands) is detected, or (ii) on the basis ofwhether or not a push-pull signal is detected from a reproduction signalobtained from the information recording media; or on the basis of themeasurement of a push-pull signal detection level (refer to a patentdocument 2 or the like).

Patent document 1: Japanese Patent Application Laid Open NO. 2001-307427Patent document 2: Japanese Patent Application Laid Open NO. Hei08-235765

DISCLOSURE OF INVENTION Subject to be Solved by the Invention

In cases where an information reproducing apparatus judges a media typein a seek operation or the like for obtaining control information, theinformation reproducing apparatus judges the type of the informationrecording medium; on the basis of whether or not a push-pull signal isdetected from a reproduction signal obtained from the informationrecording medium; or on the basis of the measured push-pull signaldetection level, as described above, in some cases. If the contentswhose copyright is protected by the CSS are recorded on therecording-type information recording medium, there is such a problemthat even if the contents are legally recorded, the informationreproducing apparatus judges that they are illegally copied contents anddoes not allow the reproduction for the aforementioned reasons in somecases.

In view of the aforementioned problems, it is therefore an object of thepresent invention to provide an information recording medium whichachieves a balance between protecting copyright for the record data,such as contents, on the recording-type information recording medium andmaintaining compatibility with the read-only type information recordingmedium.

Means for Solving the Subject

The above object of the present invention can be achieved by aninformation recording medium according to claim 1; which is an opticalrecording medium; in which a groove is formed along a recording track;and which is irradiated with a laser beam for recording or reproduction,wherein a push-pull signal less than a predetermined value, is obtainedfrom at least a partial area of the groove.

The above object of the present invention can be also achieved by amethod of manufacturing an information recording medium, according toclaim 15; in which a groove is formed along a recording track; and whichis irradiated with a laser beam for recording or reproduction; wherein apush-pull signal less than a predetermined value, is obtained from atleast a partial area of the groove, the method provided with: a changingprocess of changing a depth or width of the groove in the partial area;and an adjusting process of adjusting the push-pull signal obtained fromthe changed partial area to be less than the predetermined value.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment of InformationRecording Medium

Hereinafter, an information recording medium in an embodiment of thepresent invention will be explained.

An embodiment of the information recording medium of the presentinvention is an information recording medium; which is an opticalrecording medium; in which a groove is formed along a recording track;and which is irradiated with a laser beam for recording or reproduction,wherein a push-pull signal less than a predetermined value, is obtainedfrom at least a partial area (a reproduction setting area) of thegroove.

According to the embodiment of the information recording medium of thepresent invention, for example, at least one recording layer islaminated on a disc-shaped substrate. In a recording area in therecording layer, for example, information such as audio, videoinformation, content information, or user data can be recorded orreproduced through the groove or groove track, i.e. the recording track,by using the laser beam with a wavelength of 650 nm.

Moreover, the groove track is formed such that the push-pull signal lessthan the predetermined value is detected from at least the partial areaof the groove track.

Therefore, if an information reproducing apparatus uses the partial areaas the reproduction setting area in order to judge the type of theinformation recording medium when reproducing the information recordingmedium of the present invention, the signal is detected that is lessthan the push-pull signal obtained from a normal recording typeinformation recording medium. The “reproduction setting area” of thepresent invention herein denotes an area which is firstly accessed whenthe recorded record information such as record data is reproduced, whichallows the judgment of whether or not to allow the reproduction of therecord information, and which is to identify whether or not to berecording media.

Thus, the information recording medium of the present invention isjudged to be not the recording type information recording medium but aread-only information recording medium, such as a DVD-ROM. As a result,a conventional player can perform a reproduction process on theinformation recording medium of the present invention, as in the generalread-only information recording medium.

In one aspect of the embodiment of the information recording medium ofthe present invention, the push-pull signal obtained from the partialarea after recording, is less than the predetermined value.

According to this aspect, if the information reproducing apparatus usesthe partial area after recording (in other words, in a recorded status)in order to judge the type of the information recording medium whenreproducing the information recording medium of the present invention,the signal is detected that is less than the push-pull signal obtainedfrom the normal recording type information recording medium. Thus, theinformation recording medium of the present invention is judged to benot the recording type information recording medium but the generalread-only information recording medium, such as a DVD-ROM. As a result,the conventional player can perform the reproduction process on theinformation recording medium of the present invention after recording,as in the general read-only information recording medium.

In another aspect of the embodiment of the information recording mediumof the present invention, the predetermined value is a detection amountof the push-pull signal determined in a DVD-R standard or DVD-RWstandard.

According to this aspect, if the information reproducing apparatus usesthe partial area in order to judge the type of the information recordingmedium when reproducing the information recording medium of the presentinvention, the signal is detected that is less than the push-pull signalobtained from the recording type information recording medium accordingto the DVD-R standard or DVD-RW standard. Thus, the informationrecording medium of the present invention is judged to be not therecording type information recording medium according to the DVD-Rstandard or DVD-RW standard but the read-only information recordingmedium, such as a DVD-ROM. As a result, the conventional player canperform the reproduction process on the information recording medium ofthe present invention, as in the general read-only information recordingmedium.

In another aspect of the embodiment of the information recording mediumof the present invention, the predetermined value is a detection amountof the push-pull signal determined in a DVD+R standard or DVD+RWstandard.

According to this aspect, if the information reproducing apparatus usesthe partial area in order to judge the type of the information recordingmedium when reproducing the information recording medium of the presentinvention, the signal is detected that is less than the push-pull signalobtained from the recording type information recording medium accordingto the DVD+R standard or DVD+RW standard. Thus, the informationrecording medium of the present invention is judged to be not therecording type information recording medium according to the DVD+Rstandard or DVD+RW standard but the read-only information recordingmedium, such as a DVD-ROM. As a result, the conventional player canperform the reproduction process on the information recording medium ofthe present invention, as in the general read-only information recordingmedium.

In an aspect associated with the predetermined value, the predeterminedvalue may be equal to “0.22”; if the push-pull signal detected from thepartial area after recording, is normalized by an entire amount of lightdetected from the partial area after recording.

By virtue of such construction, if the information reproducing apparatususes the partial area after recording (in other words, in a recordedstatus) in order to judge the type of the information recording mediumwhen reproducing the information recording medium of the presentinvention, the signal is detected that is less than the predeterminedvalue, which is equal to “0.22”; if the push-pull signal detected fromthe partial area after recording is normalized by the entire amount oflight detected from the partial area after recording. Thus, theinformation recording medium of the present invention is judged to benot the recording type information recording medium but the read-onlyinformation recording medium, such as a DVD-ROM. As a result, theconventional player can perform the reproduction process on theinformation recording medium of the present invention after recording,as in the general read-only information recording medium.

In another aspect of the embodiment of the information recording mediumof the present invention, the partial area is in a radial range of “22.3to 35.0 (mm: millimeter)” from the center of the information recordingmedium.

According to this aspect, it is possible to make the partial areafunction as the reproduction setting area which is firstly accessed whenthe recorded record information such as record data is reproduced, whichallows the judgment of whether or not to allow the reproduction of therecord information, and which is to identify whether or not to berecording media. As a result, the conventional player can access thepartial area that functions as the reproduction setting area, quicklyand appropriately, and it can perform the reproduction process on theinformation recording medium of the present invention, more quickly andappropriately, as in the general read-only information recording medium.

In another aspect of the embodiment of the information recording mediumof the present invention, the partial area is an area that is notincluded in a data area.

According to this aspect, various information such as contentinformation can be appropriately recorded in the data area on the basisof a recording method and an encryption method which are substantiallythe same as conventional ones.

In an aspect associated with the partial area, the partial area may beincluded in a lead-in area.

By virtue of such construction, it is possible to make the partial areafunction as the lead-in area which is firstly accessed when the recordedrecord information such as record data is reproduced, which allows thejudgment of whether or not to allow the reproduction of the recordinformation, and which is to identify whether or not to be recordingmedia. As a result, the conventional player can access the partial areathat functions as the lead-in area, quickly and appropriately, and itcan perform the reproduction process on the information recording mediumof the present invention, more quickly and appropriately, as in thegeneral read-only information recording medium.

In an aspect associated with the partial area, the partial area may beincluded in a CDZ (control data zone)

By virtue of such construction, it is possible to make the partial areafunction as the CDZ (control data zone) which is firstly accessed whenthe recorded record information such as record data is reproduced, whichallows the judgment of whether or not to allow the reproduction of therecord information, and which is to identify whether or not to berecording media. As a result, the conventional player can access thepartial area that functions as the CDZ (control data zone), quickly andappropriately, and it can perform the reproduction process on theinformation recording medium of the present invention, more quickly andappropriately, as in the general read-only information recording medium.

In another aspect of the embodiment of the information recording mediumof the present invention, a straight groove is formed in the partialarea.

According to this aspect, if the information reproducing apparatus usesthe partial area in order to judge the type of the information recordingmedium when reproducing the information recording medium of the presentinvention, the signal is detected that is less than the push-pull signalobtained from a recording type information recording medium with thestraight groove formed. Thus, the information recording medium of thepresent invention is judged to be not the special recording typeinformation recording medium with the straight groove formed, but theread-only information recording medium, such as a DVD-ROM. As a result,the conventional player can perform the reproduction process on theinformation recording medium of the present invention, as in the generalread-only information recording medium.

In another aspect of the embodiment of the information recording mediumof the present invention, wobble is formed in the partial area.

According to this aspect, if the information reproducing apparatus usesthe partial area in order to judge the type of the information recordingmedium when reproducing the information recording medium of the presentinvention, the signal is detected that is less than the push-pull signalobtained from a recording type information recording medium with thewobble formed. Thus, the information recording medium of the presentinvention is judged to be not the recording type information recordingmedium with the wobble formed, but the read-only information recordingmedium, such as a DVD-ROM. As a result, the conventional player canperform the reproduction process on the information recording medium ofthe present invention, as in the general read-only information recordingmedium.

In another aspect of the embodiment of the information recording mediumof the present invention, wobble with a wobble frequency substantiallytwice the wobble frequency determined in a DVD-R standard or DVD-RWstandard, is formed in the partial area.

According to this aspect, if the information reproducing apparatus usesthe partial area in order to judge the type of the information recordingmedium when reproducing the information recording medium of the presentinvention, the signal is detected that is less than the push-pull signalobtained from a recording type information recording medium in which thespecial wobble with a wobble frequency substantially twice the wobblefrequency determined in the standard frequency, is formed. Thus, theinformation recording medium of the present invention is judged to benot the recording type information recording medium in which the specialwobble with a wobble frequency substantially twice the wobble frequencydetermined in the standard frequency, is formed, but the read-onlyinformation recording medium, such as a DVD-ROM. As a result, theconventional player can perform the reproduction process on theinformation recording medium of the present invention, as in the generalread-only information recording medium.

In another aspect of the embodiment of the information recording mediumof the present invention, the push-pull signal less than thepredetermined value, is obtained from an entire area (a reproductionsetting area) of the groove.

According to this aspect, if the information reproducing apparatus usesthe entire area in order to judge the type of the information recordingmedium when reproducing the information recording medium of the presentinvention, the signal is detected that is less than the push-pull signalobtained from the normal recording type information recording medium.Thus, the information recording medium of the present invention isjudged to be not the recording type information recording medium but theread-only information recording medium, such as a DVD-ROM. As a result,the conventional player can perform the reproduction process on theinformation recording medium of the present invention, as in the generalread-only information recording medium.

In another aspect of the embodiment of the information recording mediumof the present invention, the push-pull signal obtained from the partialarea, is less than a push-pull signal obtained from another partial areaof the groove.

According to this aspect, if the information reproducing apparatus usesthe partial area in order to judge the type of the information recordingmedium when reproducing the information recording medium of the presentinvention, the signal is detected that is less than the push-pull signalobtained from the normal recording type information recording medium.Thus, the information recording medium of the present invention isjudged to be not the recording type information recording mediumcorresponding to another partial area of the groove, but the read-onlyinformation recording medium, such as a DVD-ROM. As a result, theconventional player can perform the reproduction process on theinformation recording medium of the present invention, as in the generalread-only information recording medium.

(Embodiment of Method of Manufacturing An Information Recording Medium)

Hereinafter, a method of manufacturing an information recording mediumin an embodiment of the present invention will be explained.

An embodiment of the method of manufacturing an information recordingmedium of the present invention is a method of manufacturing aninformation recording medium; in which a groove is formed along arecording track; and which is irradiated with a laser beam for recordingor reproduction; wherein a push-pull signal less than a predeterminedvalue, is obtained from at least a partial area of the groove, themethod provided with: a changing process of changing a depth or width ofthe groove in the partial area (a reproduction setting area); and anadjusting process of adjusting the push-pull signal obtained from thechanged partial area to be less than the predetermined value.

According to the embodiment of the method of manufacturing aninformation recording medium of the present invention, firstly, thedepth or width of the groove in the partial area is changed in thechanging process. Then, the depth or width of the groove in the partialarea is adjusted in the adjusting process such that the push-pull signalobtained from the partial area is less than the predetermined value.Incidentally, in the adjustment of the depth or width of the groove inthe partial area, the depth or width of the groove may be changedexperimentally, experientially, theoretically, or by simulations, toobtain the push-pull signal, individually and specifically.

As a result, it is possible to manufacture the information recordingmedium in which the push-pull signal less than the predetermined valueis obtained from at least the partial area of the groove, on the basisof the changing process and the adjusting process, more simply andhighly accurately.

Incidentally, in response to the various aspects of the embodiment ofthe information recording medium of the present invention describedabove, the embodiment of the method of manufacturing an informationrecording medium of the present invention can also adopt variousaspects.

In one aspect of the embodiment of the method of manufacturing aninformation recording medium of the present invention, the predeterminedvalue is a detection amount of the push-pull signal determined in aDVD-R standard or DVD-RW standard.

According to this aspect, it is possible to manufacture the informationrecording medium in which the push-pull signal less than thepredetermined value according to the DVD-R standard or DVD-RW standardis obtained from at least the partial area of the groove, on the basisof the changing process and the adjusting process, more simply andhighly accurately.

In another aspect of the embodiment of the method of manufacturing aninformation recording medium of the present invention, the predeterminedvalue is equal to “0.22”; if the push-pull signal detected from thepartial area after recording is normalized by an entire amount of lightdetected from the partial area after recording.

According to this aspect, it is possible to manufacture the informationrecording medium in which the push-pull signal is obtained that is lessthan the predetermined value, which is equal to “0.22” if the push-pullsignal detected from the partial area after recording is normalized bythe entire amount of light detected from the partial area afterrecording, from at least the partial area of the groove, on the basis ofthe changing process and the adjusting process, more simply and highlyaccurately.

In another aspect of the embodiment of the method of manufacturing aninformation recording medium of the present invention, the changingprocess changes the width of the groove in the partial area to “½ (i.e.one halt)” or less of a track interval of the recording track, and theadjusting process adjusts the push-pull signal obtained from the changedpartial area to be less than the predetermined value.

According to this aspect, it is possible to manufacture the informationrecording medium in which the push-pull signal less than thepredetermined value is obtained from at least the partial area of thegroove, on the basis of the changing process and the adjusting process,more simply and highly accurately, on the basis of the width of thegroove in the partial area which is changed to “½ (i.e. one half)” orless of the track interval of the recording track.

In another aspect of the embodiment of the method of manufacturing aninformation recording medium of the present invention, the changingprocess changes the depth of the groove in the partial area to “¼ (i.e.a quarter or one-forth)” or less of the groove width, and the adjustingprocess adjusts the push-pull signal obtained from the changed partialarea to be less than the predetermined value.

According to this aspect, it is possible to manufacture the informationrecording medium in which the push-pull signal less than thepredetermined value is obtained from at least the partial area of thegroove, on the basis of the changing process and the adjusting process,more simply and highly accurately, on the basis of the depth of thegroove in the partial area which is changed to “¼” or less of the groovewidth.

As explained above, according to the embodiment of the informationrecording medium of the present invention, the groove is formed alongthe recording track, and the push-pull signal less than thepredetermined value is obtained from at least the partial area (thereproduction setting area) of the groove. As a result, the conventionalplayer can perform the reproduction process on the information recordingmedium of the present invention, as in the general read-only informationrecording medium.

According to the embodiment of the method of manufacturing aninformation recording medium of the present invention, it is providedwith the changing process and the adjusting process. As a result, it ispossible to manufacture the information recording medium in which thepush-pull signal less than the predetermined value is obtained from atleast the partial area of the groove, on the basis of the changingprocess and the adjusting process, more simply and highly accurately.

The operation and other advantages of the present invention will becomemore apparent from examples explained below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view showing the basic structure of anoptical disc having a plurality of recording areas in an example of theinformation recording medium of the present invention, and a schematicconceptual view showing a recording area structure in the radialdirection associated with the cross sectional view.

FIG. 2 is a conceptual graph showing a relation between a recording areaof the optical disc in the example of the information recording mediumof the present invention and an address which can specify the positionof the recording area.

FIG. 3 are graphs schematically showing a direction which changes thewidth and the depth of a groove in the example of the informationrecording medium of the present invention (FIG. 3( a) and FIG. 3( b)).

FIG. 4 are graphs schematically showing a change in the value of apush-pull signal and a change in the ratio of the value of the push-pullsignal when the absolute value of the width or depth is defined in theexample of the information recording medium of the present invention(FIG. 4( a) and FIG. 4( b)).

FIG. 5 are a table numerically showing a correlation among a pigmentfilm thickness, a groove depth, a groove width, a track interval, apush-pull signal detection amount after recording, and a normalizedpush-pull signal value in the example of the information recordingmedium of the present invention (FIG. 5( a)), and a table showing aresult when reproduction is tried by an information reproducingapparatus which can judge the type of an optical disc at a push-pullsignal amplitude (detection level), with respect to the recording-typedisc on which contents protected by CSS are recorded, in the example ofthe information recording medium of the present invention (FIG. 5( b)).

FIG. 6 is a block diagram showing the entire structure of an informationrecording/reproducing apparatus 200 in the example of the informationrecording medium of the present invention.

FIG. 7 is a schematic diagram schematically showing a procedure ofmanufacturing the information recording medium of the present invention.

DESCRIPTION OF REFERENCE CODES

-   1 center hole-   50 track-   51 ECC block-   100 optical disc-   101 lead-in area-   101 a reproduction setting area-   102 data area-   103 lead-out area-   200 information recording/reproducing apparatus-   CDZ control data zone-   RMA recording management area

EXAMPLES

Hereinafter, examples of the present invention will be explained on thebasis of the drawings.

(1) First Example of Information Recording Medium

Next, with reference to FIG. 1 to FIG. 6, a first example of theinformation recording medium of the present invention will be explainedin detail.

(1-1) Basic Structure

Firstly, with reference to FIG. 1, the basic structure of an opticaldisc in the example of the information recording medium of the presentinvention will be explained. FIG. 1 is a schematic plan view showing thebasic structure of the optical disc having a plurality of recordingareas in an example of the information recording medium of the presentinvention, and a schematic conceptual view showing a recording areastructure in the radial direction associated with the cross sectionalview.

As shown in FIG. 1, an optical disc 100 has a recording surface on adisc main body with a diameter of about 12 cm, as in a DVD, for example.On the recording surface, the optical disc 100 is provided with a centerhole 1 as the center; (i) a power calibration area PCA; (ii) a recordingmanagement area RMA; (iii) a lead-in area 101 having a control data zoneCDZ and a narrow burst cutting area NBCA; (iv) a data area 102; and (v)a lead-out area 103.

Incidentally, as described later, one specific example of the “partialrecording area” of the present invention is the aforementioned recordingmanagement area RMA or the lead-in area such as the control data zoneCDZ. Moreover, the narrow burst cutting area NBCA is a recording area inwhich judgment information is recorded in advance, wherein the judgmentinformation allows various attributes of the optical disc to be judged.More specifically, the NBCA allows the judgment information to berecorded at low density in a barcode shape over a plurality of tracks,and the NBCA also allows the judgment information to be reproduced onlyby rotational control for the optical disc, without tracking control. Asa specific example of the judgment information using the NBCA, forexample, a manufacturing number unique to each optical disc 100, i.e. amedia ID, or the like can be listed.

Moreover, at least one recording layer is laminated, for example, on atransparent substrate not illustrated of the optical disc 100. In eachrecording area of the recording layer, for example, tracks 50 such as agroove track and a land track are alternately provided, spirally orconcentrically, centered on the center hole 1. Moreover, on the tracks50, record information (data) is divided and recorded by a unit of ECCblock 51. The ECC (Error Correction Code) block 51 is a recordinformation management unit by which the data can be error-corrected.

In particular, in the data area 102, first encryption information, suchas a title key, based on an encryption system, such as CSS, andencrypted contents encrypted by the first encryption information, suchas a title key, are recorded. More specifically, the first encryptioninformation such as a title key is encrypted by second encryptioninformation such as a disc key and a disc key set.

Incidentally, the present invention is not particularly limited to theoptical disc having the five areas. For example, even if the lead-inarea 101 or the lead-out area 103 does not exist, the data structure orthe like explained below can be established. Moreover, the lead-in area101 or the lead-out area 103 may be further segmentalized.

(1-2) Address Which Can Specify Position of Recording Area of OpticalDisc

Next, with reference to FIG. 2, an explanation will be given on arelation between a recording area of the optical disc and an addresswhich can specify the positions of the recording areas. FIG. 2 is aconceptual graph showing the relation between the recording area of theoptical disc in the example of the information recording medium of thepresent invention and the address which can specify the position of therecording area. Incidentally, the vertical axis denotes an address valuesuch as a sector number and a land pre-pit address, and the horizontalaxis denotes a relative position in the radial direction of the opticaldisc.

As shown in FIG. 2, the recording areas of the optical disc 100 in theexample of the information recording medium of the present invention areprovided with (i) the power calibration area PCA; (ii) the recordingmanagement area RMA; (iii) the lead-in area 101 having the control datazone CDZ; (iv) the data area 102; and (v) the lead-out area 103, fromthe inner side to the outer side, as described above. Incidentally, inthe RMA and the CDZ, various management information may be recorded. Themanagement information is various information for managing theinformation recording medium, such as (ii-1) information about recordingfeatures such as an optimum recording power, (ii-2) attributeinformation for specifying the type of media, and (ii-3) information forspecifying the positions of various recording areas. In particular, anencryption key in the present invention may be recorded in advance (i.e.prerecorded), for example, in the CDZ, under management by a contentholder. On the other hand, the record data such as contents encrypted bythe encryption key may be recorded by an informationrecording/reproducing apparatus which corresponds to the optical discand which will be described later.

Moreover, as shown in FIG. 2, for example, if the address which canuniquely specify the position of the recording area of theaforementioned optical disc 100 is a physical sector number (or a sectornumber) of sectors which constitute the ECC block, the address in therecording areas of the optical disc 100 may be increased as an opticalpickup is displaced from the inner side to the outer side (refer to athick solid line in FIG. 2). Alternatively, for example, if the addresswhich can uniquely specify the position of the recording area is a landpre-pit address, the address in the recording areas of the optical disc100 may be reduced as the optical pickup of the informationrecording/reproducing apparatus described later is displaced from theinner side to the outer side (refer to a thin dotted line).

(1-3) Radial Position of Reproduction Setting Area In Which SpecialGroove is Formed

Next, an explanation will be given on the radial position of areproduction setting area 101 a; in which a special groove is formed ina partial area; which is firstly accessed when the recorded recordinformation is reproduced; and which is to identify whether or not toallow the reproduction of the record information, in the example.

Specifically, in at least one of the following two types of radialpositions, the groove is preferably formed that is defined to obtain apush-pull signal; in which at least one of its width and depth is lessthan or equal to a predetermined value. In other words, the first typeis a radial position of “22.3 (mm: millimeter) to 35 (mm)” from thecenter of the optical disc. The second type is a radial position of“22.6 (mm: millimeter) to 35 (mm)” from the center of the optical disc.In particular, at these radial positions, the depth of the groove in thegroove track, is preferably shallower (i.e. less) than a standardquantity.

This is derived from the following reason; namely, in the DVD-ROMregulation (or standard), the following two conditions need to besatisfied. The first condition is that the radial position of the startposition of the lead-in area is located inner than 22.6 (mm) from thecenter of the optical disc. The second condition is that the radialposition of the outermost portion of the recording area with informationrecorded, is located outer than 35 (mm) from the center of the opticaldisc.

On the other hand, in the regulation (or standard) of the conventionalsingle-layer recording type optical disc (i.e. DVD-R SL (i.e. SingleLayer)) and dual-layer recording type optical disc (i.e. DVD-R DL), thefollowing three conditions need to be satisfied. The first condition isthat the start radial position of the recording management area is about22.3 (mm) from the center of the optical disc. The second condition isthat the radial position of the start position of the lead-in area isabout 22.6 (mm) from the center of the optical disc. The third conditionis that radial position of the outermost circumference of the recordingarea with information recorded, is outer than 35 (mm) from the center ofthe optical disc.

Moreover, for example, the area which is firstly accessed when therecorded record information such as record data is reproduced; whichallows the judgment of whether or not to allow the reproduction of therecord information; and in which a laser beam is focused to identifywhether or not to be recording media; is preferably placed in a placewhere information has been recorded, for the purpose of realizing aquick reproduction operation.

As described above, on the basis of the aforementioned six (=2+3+1)conditions, it is preferable to make the depth of the groove in thegroove track shallower (i.e. less) than the standard quantity; such thatthe detection amount of the push-pull signal is less than apredetermined amount (i.e. a value that satisfies the DVD-R standard),at least at the radial position of “22.6 (mm) to 35 (mm)” from thecenter of the optical disc. Moreover, for an information recordingapparatus (i.e. recorder), it is preferable to make the depth of thegroove in the groove track shallower (i.e. less) than the standardquantity, at the radial position of “22.3 (mm) to 35 (mm)” from thecenter of the optical disc.

Incidentally, the standard quantity herein indicates the depth of thegroove in the groove track which is set to the extent that can detectthe push-pull signal satisfying the DVD-R standard described later.Moreover, the depth of the groove not only in the partial groove trackbut also in the entire groove track, may be uniformly set shallow.

Moreover, incidentally, the entire recording area or partial recordingarea, such as the reproduction setting area, may be set to have astraight groove shape; in which there is no wobble; and in which atleast the depth of the groove in the groove track is reduced.Alternatively, wobble may be formed which has a frequency sufficientlyhigher (e.g. twice or more higher) than a wobble frequency determined inthe DVD-R standard. The important thing is that the recording area isshaped such that the wobble cannot be detected by a general reproducingapparatus for DVD-R. This is because there is possibly a reproducingapparatus for performing medium judgment not only on the basis of thedetection amount of the push-pull signal but also on the basis of thepresence or absence of the wobble, in the disc type judgment. Thus, bysetting the detection amount of the push-pull signal to be less than theaforementioned predetermined value; and by constituting the recordingarea not to detect the wobble; the possibility increases that allows thereproduction apparatus to identify that the information recording mediumof the present invention is the DVD-ROM disc.

(1-4) One Specific Example of Groove Structure

Next, with reference to FIG. 3 to FIG. 5, one specific example of agroove structure in the example of the present invention will beexplained.

(1-4-1) Groove Shape

Firstly, with reference to FIG. 3 and FIG. 4, one specific example ofthe groove shape in the example of the present invention will beexplained. FIG. 3 are graphs schematically showing a direction whichchanges the width and the depth of the groove in the example of theinformation recording medium of the present invention (FIG. 3( a) andFIG. 3( b)). FIG. 4 are graphs schematically showing a change in thevalue of the push-pull signal and a change in the ratio of the value ofthe push-pull signal; when the absolute value of the width or depth isdefined in the example of the information recording medium of thepresent invention (FIG. 4( a) and FIG. 4( b)).

As shown in FIG. 3( a) and FIG. 3( b), the groove shape in the example,is defined to reduce at least the absolute value of the width or thedepth in the aforementioned reproduction setting area of the entiregroove track. By reducing the width or depth of the groove track in thereproduction setting area as described above, it is possible to make adetection level (i.e. amplitude level) of a push-pull signal lower thana value obtained from the general optical disc such as a DVD-R.

In general, in the standard of the recording type optical disc such as aDVD-R, the following conditional expressions (1) and (2) are defined tobe satisfied, if the value (or level) of the normalized push-pull signalwith information recorded in the recording area, is NPPa (i.e. NormalPush-Pull signal after); and the value of the normalized push-pullsignal without information recorded in the recording area, is NPPb (i.e.Normal Push-Pull signal before).

0.22<NPPb<0.44  (1)

0.5<NPPr<1.0  (2)

(wherein, NPPr=NPPb/NPPa)

From the aforementioned two conditional expressions, the followingconditional expression (3) is derived.

0.22<NPPa<0.88  (3)

Incidentally, the “normalization>” in the example, denotes a relativevalue of the detection level of the push-pull signal received in oneportion of a light receiving element; if the total amount of thedetection level of the push-pull signal on the entire light receivingelement, is “1.0”. Specifically, in the case that the amounts of lightreceived from four areas of a four-divisional light receiving element(e.g. photo detector) described later are “Ia”, “Ib”, “Ic”, and “Id”,respectively; the value of NPPa after recording and the value of NPPbbefore recording are defined by the following equations (4a) and (4b),respectively.

NPPa=|(Ia+Ib)−(Ic+Id)|/|Ia+Ib+Ic+Id|  (4a)

NPPb=|(Ia+Ib)−(Ic+Id)|/|Ia+Ib+Ic+Id|  (4b)

As described above, for example, in the DVD-R, the width and depth ofthe groove track are provided to obtain the push-pull signal having thepredetermined value, from the recording area such as the RMA (recordingmanagement area) or the reproduction setting area.

In contrast, in the optical disc in the example, by adjusting at leastone of the width and depth of the groove track; an amplitude of thepush-pull signal obtained from at least one portion of the recordingarea such as the RMA or the reproduction setting area, is reduced to beless than the predetermined value. More specifically, the predeterminedvalue may denote an amplitude that is substantially equivalent to theamplitude of the push-pull signal obtained from DVD-R, for example.Incidentally, in the aforementioned specific example, the predeterminedvalue denotes an amplitude with a NPPb being as a value of “0.22”.

In addition, according to quantitative analysis by the presentinventors; it is found that the detection level of the push-pull signalcan be reduced by reducing the width or the depth of the groove track inthe reproduction setting area (refer to FIG. 3 and FIG. 4).Specifically, it is found that the detection level of NPPa can bereduced, for example; by adjusting the depth of the groove track from140 (nm: nanometer) which is general value, to 100 (nm).

When reproducing the record information recorded in the partial area ofthe recording area including the reproduction setting area; aconventional player (i.e. general information recording/reproducingapparatus) obtains only a signal with a smaller value than the push-pullsignal obtained from the recording type information recording medium; sothat the general information recording/reproducing apparatus judges thatthe information recording medium of the present invention is not arecording type disc but a read-only information recording medium such asa DVD-ROM. As a result, the conventional player can perform areproduction process on the information recording medium of the presentinvention, as same as in the general read-only information recordingmedium such as a DVD-ROM.

As a result, owing to the aforementioned recording type informationrecording medium, which is defined to obtain the push-pull signal inwhich at least one of the width and depth of the track has the absolutevalue that is less than or equal to the predetermined value; it allowsgeneral users to be supplied with the contents whose copyright isprotected by the encryption system, such as CSS; and it allows thesupplied contents to be reproduced by a conventional playerappropriately and simply. Therefore, according to the informationrecording medium of the present invention, it is possible to achieveboth protecting copyright for the contents and maintaining reproductioncompatibility.

Incidentally, the groove may be formed being defined to obtain thepush-pull signal which is less than or equal to the predetermined value,from not only the partial groove track but also the entire groove track.

As a result, without being influenced by the position of thereproduction setting area described above, the conventional player canperform the reproduction process on the information recording medium ofthe present invention, as in the general read-only information recordingmedium.

(1-4-2) Groove Shape and Structure

Next, with reference to FIG. 5, one specific example of the groove shapeand structure in the example of the present invention, will beexplained. FIG. 5( a) is a table numerically showing a correlation amonga thickness of a pigment film (Abs), a groove depth (nni), a groovewidth (nm), a track interval (mm), a detection amount of a push-pullsignal after recording (mV), and a normalized push-pull signal value(NPPa) in the example of the information recording medium of the presentinvention. Incidentally, “Abs” is a unit indicating light absorbance(i.e. the degree of absorption of the light), and it is used as an indexindicating the film thickness (i.e. thickness) of the pigment film.Specifically, the smaller the value of “Abs” is, the thinner thethickness of the pigment film is. FIG. 5( b) is a table showing aresult; when reproduction is tried by an information reproducingapparatus which can judge the type of an optical disc at a amplitude(i.e. detection level) of the push-pull signal, with respect to therecording-type disc on which contents protected by CSS are recorded, inthe example of the information recording medium of the presentinvention.

According to the study by the present inventors, as shown in detectionresults in “Disc A” and “Disc B” in FIG. 5( a); it is found that if thethickness of the pigment film is reduced without a change in the depthof the groove, the detection amount of the push-pull signal decreases.

Moreover, as shown in detection results in “Disc B”, “Disc C”, and “DiscD” in FIG. 5( a); it is found that if the depth of the pigment filmreduces without a change in the thickness of the groove, the detectionamount of the push-pull signal reduces.

As a result, as shown in results in “Recorder (1)”, “Recorder (2)”,“Writer (1)”, and “Writer (2)” in FIG. 5( b), on the basis of thisstudy; it can be found that many or most of information reproducingapparatuses or information recording/reproducing apparatuses to be ableto judge the type of the optical disc at the push-pull signal amplitude(i.e. detection level), judge the type not to be the recording typeoptical disc such as a DVD-R but to be the readonly type optical discsuch as a DVD-ROM; if the value of NPPa of the loaded optical disc isnear “0.183”. In other words, it can be proved that many or most ofinformation reproducing apparatuses or information recording/reproducingapparatuses, reproduce DVD-R media; in which the contents protectedunder the CSS encryption system are recorded.

From the aforementioned study; it is found that the push-pull signalobtained from the information recording medium, has the amplitude thathas the predetermined value or less; by setting the width of the grooveto about “½” or less of the track interval of the recording tracks; andby setting the depth of the groove to about “¼” or less of the groovewidth. As a result, it can be proved; that the aforementionedinformation recording medium of the present invention is judged to bethe read-only type optical disc such as a DVD-ROM, on many or most ofinformation reproducing apparatuses or information recording/reproducingapparatuses.

(2) Information Reproducing Apparatus

Next, with reference to FIG. 6, an example of the informationreproducing apparatus of the present invention will be explained indetail. In particular, in the example, the information reproducingapparatus of the present invention is applied to an informationrecording/reproducing apparatus for optical discs.

(2-1) Basic Structure

Firstly, with reference to FIG. 6, an explanation will be given on thebasic structure of an information recording/reproducing apparatus 200 inthe example of the information reproducing apparatus of the presentinvention. FIG. 6 is a block diagram showing the entire structure of theinformation recording/reproducing apparatus 200 in the example of theinformation recording medium of the present invention.

The information recording/reproducing apparatus 200 is provided with theoptical disc 100, an optical pickup 202, a spindle motor 203, a headamplifier 204, a sum generation circuit 210, a mark data demodulationcircuit 211, a mark data correction circuit 212, a buffer 213, aninterface 214, a push-pull signal generation circuit 220, a low passfilter 221, and a servo unit 222.

In the optical disc 100, mark data DP synchronized with a first clocksignal CK1 is recorded by the length of a record mark MK. The firstclock signal CK1 of a RF reproduction signal component is a signal thatcan be generated by the information recording/reproducing apparatus 200from the RF reproduction signal component of the optical disc 100 whichvaries in an almost constant cycle in accordance with wobbling or thelike. In the example, the first clock signal CK1 is generated by themark data demodulation circuit 211. Incidentally, in the example, therecord mark MK can be interpreted as a pit, and the track is formed ofthis pit row.

The information recording/reproducing apparatus 200 is, morespecifically, provided with the optical disc 202 for irradiating areproduction beam on the optical disc 100 and for outputting a signalcorresponding to reflected light; the spindle motor 203 for controllingthe rotation of the optical disc 100; and the servo unit 222. The servounit 222 is supplied with the first clock signal CK1 and a marksynchronization signal SYNCp. The servo unit 222 performs tracking servoand focus servo for performing relative positional control with respectto the optical disc 100 of the optical pickup 202, and spindle servo forcontrolling the rotation of the spindle motor 203, in synchronizationwith these signals.

The optical pickup 202 is provided with a four-divisional detectioncircuit not illustrated and a laser diode for irradiating a reproductionbeam. The four-divisional detection circuit divides the reflected lightof the reproduction beam into areas 1A, 1B, 1C, and 1D shown in theupper part of FIG. 6, and it outputs, to each area, a signalcorresponding to the amount of light in each area. The head amplifier204 amplifies each output signal from the optical pickup 202 and outputsa divisional reading signal 1 a corresponding to the area 1A, adivisional reading signal 1 b corresponding to the area 1B, a divisionalreading signal 1 c corresponding to the area 1C, and a divisionalreading signal 1 d corresponding to the area 1D.

The sum generation circuit 210 is provided with an addition circuit foradding the divisional reading signals 1 a, 1 b, 1 c, and 1 d and foroutputting a sum reading signal SRF. Incidentally, the sum readingsignal SRF is a signal denoting the length of the record mark.

The mark data demodulation circuit 211 reproduces the mark data DP onthe basis of the sum reading signal SRF and generates the first clocksignal CK1. More specifically, the mark data demodulation circuit 211generates reproduction data by demodulating the reproduced mark data DPwith a predetermined table, with the mark synchronization signal SYNCpused as a reference position. For example, if RLL (1, 7) modulation,i.e. Run Length Limited (1, 7) Modulation is adopted as a modulationmethod, such a process that converts 3-bit mark data DP to 2-bitreproduction data is performed. Moreover, a descramble process isperformed in which the order of the reproduction data is rearranged inaccordance with a predetermined rule, and the processed reproductiondata is outputted.

The reproduction data obtained in this manner is supplied to the markdata correction circuit 212 where an error correction process, aninterpolation process, or the like is performed, and then, it is storedin the buffer 213. The interface 214 sequentially reads the data storedin the buffer 213, converts it into a predetermined format, and outputsit to external equipment.

The push-pull signal generation circuit 220 calculates (1 a+1 d)−(1 b+1c) to generate the push-pull signal. The component (1 a+1 d) correspondsto the areas 1A and 1D on the left side with respect to a readingdirection, while the component (1 b+1 c) corresponds to the areas 1B and1C on the right side with respect to the reading direction. The value ofthe push-pull signal represents a relative positional relation betweenthe reproduction beam and the track.

The push-pull signal is outputted to the servo unit 222 through the lowpass filter 221. The servo unit 222 performs tracking control on thebasis of the push-pull signal. Specifically, the value of the push-pullsignal standardized can be calculated by the following equation (5) onthe push-pull signal generation circuit 220.

“value of the push-pull signalstandardized”={(1a+1d)−(1b+1c)}/(1a+1b+1c+1d)  (5)

As shown in the equation (5), the value of the push-pull signalstandardized is calculated on a division circuit for outputting aquotient obtained by dividing the push-pull signal by the sum of thepush-pull signals. On the basis of the push-pull signal outputted fromthis arithmetic circuit, it is possible to obtain the stable push-pullsignal in which a variation in the absolute value of the push-pullsignal is corrected and in which the variation is caused by a change inlocal reflectance before or after the user data is recorded.Incidentally, in terms of the circuit, the aforementioned push-pullsignal value PP denotes the amplitude (Peak to peak value) of a signaloutputted from the low pass filter of the signal of (1 a+1 d)−(1 b+1 c).On the other hand, the value NPP of the push-pull signal standardizeddenotes the amplitude (Peak to peak value) of a signal outputted fromthe low pass filter of the signal of {(1 a+1 d)−(1 b+1 c)}/(1 a+1 b+1c+1 d). Incidentally, in the lower part of FIG. 6, the radial directionis shown in a direction along the areas 1A and 1B, and the tangentialdirection is shown in a direction along the areas 1A and 1D.

(3) Manufacturing Procedure (Change in Groove Shape of Groove Track)

Next, with reference to FIG. 7, as a manufacturing procedure, anexplanation will be given on a local change in the width and/or depth ofthe groove, which is the groove shape of the groove track. FIG. 7 is aschematic diagram schematically showing a procedure of manufacturing theinformation recording medium of the present invention.

As shown in a step 1 in FIG. 7, in a glass plate, so-called spin coatingis performed, in which viscous photoresist (e.g. photosensitive resin)is dropped and applied with a uniform thickness while the glass plate isrotated.

Then, as shown in a step 2 in FIG. 7, a portion 20 a of the glass platefor changing the groove shape is irradiated with a cutting laser beam,such as electron rays and ultraviolet rays, with a relatively low power,compared to a laser power in a portion 102 a of the glass plate forforming the data area. In the portion irradiated with the cutting laserbeam as described above, the bonding of the photoresist is cut by thelight energy at molecular level. Thus, holes are provided by dipping itin a developing solution, and a cutting portion is formed in each of theportion 20 a and the portion 102 a.

As a result, it is possible to relatively reduce the width and the depthof the groove in the portion 20 a of the glass plate for changing thegroove shape. Specifically, the width of the groove can be determined bythe beam diameter of the cutting laser beam in addition to the laserpower. Moreover, the depth of the groove can be determined by thethickness of the photoresist in addition to the laser power.Incidentally, the laser power desirably appropriately corresponds to thesensitivity of the photoresist which constitutes the plate.

Then, as shown in a step 3 in FIG. 7, nickel is laminated on a thin filmof nickel in an electroforming process, and a thick nickel layer isformed on the glass plate.

Then, as shown in a step 4 in FIG. 7, the nickel layer is peeled off theglass plate to prepare a master stampa. From the master stampa, a motherstampa and a baby stampa are prepared through the same electroformingprocess. The baby stampa is through the transfer twice, sothat it hasthe same unevenness as in the mother stampa.

Then, as shown in a step 5 in FIG. 7, a resin substrate, i.e. apolycarbonate substrate, is prepared from the baby stampa by aninjection molding machine.

Lastly, as shown in a step 6 in FIG. 7, a reflective film is applied.For example, a dummy substrate or a substrate for holding a signalsurface is applied to prepare the optical disc.

As a result of the aforementioned manufacturing procedure, it ispossible to locally change at least one of the width and depth of thegroove, which is the groove shape of the groove track of the informationrecording medium of the present invention. In other words, it ispossible to relatively reduce the width of the groove in the groovetrack, which is one portion of the recording area, such as thereproduction setting area, in the information recording medium of thepresent invention, compared to the width of the groove in the groovetrack in the data area 102. In addition, it is possible to relativelyreduce the depth of the groove in the groove track, which is one portionof the recording area, such as the reproduction setting area, in theinformation recording medium of the present invention, compared to thedepth of the groove in the groove track in the data area 102. As aresult, in the manufacturing procedure of an apparatus for manufacturingthe information recording medium of the present invention, the glassplate is irradiated with the cutting laser beam with a laser powerlocally different, so that it is possible to locally change at least oneof the width and depth of the groove, which is the groove shape of thegroove track of the information recording medium of the presentinvention. Incidentally, the width and depth of the groove, which is thegroove shape of the groove track of the information recording medium ofthe present invention, may be not only locally changed but alsouniformed as a result. It is only necessary to adjust the width or depthof the groove in the groove track such that at least the push-pullsignal detected from the reproduction setting area is less than thepush-pull signal detected from the recording type information recordingmedium such as a DVD-R.

In the aforementioned examples, as one specific example of theinformation recording medium, an explanation is given on thesingle-layer type optical disc in which recording or reproduction can beperformed by a laser beam such as Blu-rays, red LD light, or infraredrays. In addition, the present invention can be also applied to amultilayer type (multiple layer type) optical disc provided with two ormore recording layers. Moreover, it can be also applied to other variousinformation recording media which support high-density recording or ahigh transfer rate.

Moreover, the aforementioned examples describe the case where thepresent invention is applied particularly to a DVD-R as the informationrecording medium; however, the present invention is not limited to thisexamples and can be also applied to a DVD-RW, a DVD+R, and a DVD-RW.

The pesent invention is not limited to the aforementioned examples, butvarious changes may be made, if desired, without departing from theessence or spirit of the invention which can be read from the claims andthe entire specification. An information recording medium and a methodof manufacturing the information recording medium, all of which involvesuch changes, are also intended to be within the technical scope of thepresent invention.

INDUSTRIAL APPLICABILITY

The information recording medium and the method of manufacturing theinformation recording medium of the present invention can be applied toan information recording medium such as a DVD (Digital Versatile Disc),a BD (Blu-ray Disc), and a CD (Compact Disc), in which recording andreproduction can be performed by irradiating a laser beam.

1-19. (canceled)
 20. An information recording medium; which is anoptical recording medium; in which a groove is formed along a recordingtrack; and which is irradiated with a laser beam for recording orreproduction, wherein a push-pull signal less than a predeterminedvalue, is obtained from at least a partial area of the groove; thepredetermined value is equal to “0.22”; if the push-pull signal detectedfrom the partial area, is normalized by an entire amount of lightdetected from the partial area.
 21. The information recording mediumaccording to claim 20, wherein the predetermined value is a detectionamount of the push-pull signal determined in a DVD-R standard or DVD-RWstandard.
 22. The information recording medium according to claim 20,wherein the predetermined value is a detection amount of the push-pullsignal determined in a DVD+R standard or DVD+RW standard.
 23. Theinformation recording medium according to claim 20, wherein the partialarea is in a radial range of “22.3 to 35.0 (mm: millimeter)” from thecenter of said information recording medium.
 24. The informationrecording medium according to claim 20, wherein the partial area is anarea that is not included in a data area.
 25. The information recordingmedium according to claim 20, wherein the partial area is included in alead-in area.
 26. The information recording medium according to claim20, wherein the partial area is included in a CDZ (control data zone)27. The information recording medium according to claim 20, wherein astraight groove is formed in the partial area.
 28. The informationrecording medium according to claim 20, wherein wobble is formed in thepartial area.
 29. The information recording medium according to claim20, wherein wobble with a wobble frequency substantially twice thewobble frequency determined in a DVD-R standard or DVD-RW standard, isformed in the partial area.
 30. The information recording mediumaccording to claim 20, wherein the push-pull signal less than thepredetermined value, is obtained from an entire area of the groove. 31.The information recording medium according to claim 20, wherein thepush-pull signal obtained from the partial area, is less than apush-pull signal obtained from another partial area of the groove.
 32. Amethod of manufacturing an information recording medium; in which agroove is formed along a recording track; and which is irradiated with alaser beam for recording or reproduction; wherein a push-pull signalless than a predetermined value, is obtained from at least a partialarea of the groove; the predetermined value is equal to “0.22”; if thepush-pull signal detected from the partial area, is normalized by anentire amount of light detected from the partial area, said methodcomprising: a changing process of changing a depth or width of thegroove in the partial area; and an adjusting process of adjusting thepush-pull signal obtained from the changed partial area to be less thanthe predetermined value.
 33. The method of manufacturing an informationrecording medium according to claim 32, wherein the predetermined valueis a detection amount of the push-pull signal determined in a DVD-Rstandard or DVD-RW standard.
 34. The method of manufacturing aninformation recording medium according to claim 32, wherein saidchanging process changes the width of the groove in the partial area to“½” or less of a track interval of the recording track, and saidadjusting process adjusts the push-pull signal obtained from the changedpartial area to be less than the predetermined value.
 35. The method ofmanufacturing an information recording medium according to claim 32,wherein said changing process changes the depth of the groove in thepartial area to “¼” or less of the groove width, and said adjustingprocess adjusts the push-pull signal obtained from the changed partialarea to be less than the predetermined value.